Light follows a complex, but not very long path from the cornea to the brain. First, of course, light hits the cornea, or the transparent section of the eye joined with the sclera. The sclera is the hard white section of the eye. Just beneath the cornea are two more sections: the iris and the pupil. The pupil is the hole through which light travels into the eye. The iris is the colored ring around it. The iris and other ligaments, or muscles, expand or contract the iris, varying the amount of light that enters. The light has now passed through all of the visible sectors of the eye and is now inside.

After the pupil is the lens. The lens is what focuses the light. Lenses are found everywhere and there are two main types: convex and concave. Convex lenses refract the beams closer to each other so each one eventually crosses in a focal point. Concave lenses refract the beams away from each other and never create a focal point. The lens in our eye is a convex lens. After the beams pass through the lens, they hit the retina, a section of light-sensitive cells. The image is then reflected along the optic nerve to the brain. Unfortunately, the image is upside down, because of the crossing, so the brain has to flip the image to make everything look right.
Seeing at my Chaffee Zoo was a very interesting experience. After the snack after the bird show, we all went to find our animals. There were three different animals in out group, and two were at the reptile house, so we went there first. My animal is a blue duiker; kind of like a small antelope, so it obviously was not at the reptile house. Unfortunately, after we went to the reptile house, the blue duiker enclosure was on the opposite end of the zoo. We walked across the zoo, using stations as our reference points. 

When we got to the corner, saw a duck exhibit. Looking at the map, we realized we needed to walk across a small footbridge. At the blue duiker enclosure, all we apparently saw were the tortoises it was supposed to share the exhibit with. Then one of our group members saw it behind a bush. That makes sense, because blue duikers' main defense against predators is their ability to quickly disappear into the bushes when frightened. Seeing the duiker was a shock. All of the images we worked with gave an impression 3 or 4 times too large! The blue duiker is supposed to be the world's smallest antelope, and now my group and I understand why.
To understand how rainbows form, it is first necessary to understand the concept of color. Visible light is a small part of a huge scale of electromagnetic waves. Waves of visible light that have different wavelengths are different colors. The longer the wavelength, the closer to red. The shorter the wavelength, the closer to violet. White light is made up of all of the different wavelengths. Black is formed when none of them are present. White light can be refracted into the 7 main wavelengths that made it up: red, orange, yellow, green, blue, indigo, and violet.

There are a few things that can separate light in that way. One is a prism, a specially shaped object of glass. The other is water droplets. When it rains, and the sun emits white light, the droplets refract the light into the main colors of visible light. This creates a rainbow. The most commonly used definition for the criteria for a rainbow is for the sun to shine while it rains, but any combination of water and light has the potential to create one.
The sky is blue because of the process of scattering. Scattering is where a material or group of materials diffuses the light and transmits it differently. The higher a wave's frequency, the more it is scattered. Frequency is the amount of time it takes for a wave to pass the same point twice. The shorter the wavelength, or distance between two identical points on a wave, the higher the frequency. Light is radiated from the sun and across space to Earth. When on Earth, it reaches the atmosphere. The atmosphere is very different from the vacuum that is space, and the gasses have a curious effect on the light rays. 

Blue is one of the waves of visible light with the highest frequency. Visible light is a small sector on the electromagnetic spectrum, but the different wavelengths inside of it create all different types of colors. The seven main ones are red, orange, yellow, green, blue, indigo, and violet; in order of increasing frequency. Since blue has a high frequency, it is scattered throughout the sky and creates the layer of light blue.
I don't know why the sky is blue, but I have a few ideas. I know that the oceans are relatively bluish, even though water is naturally clear, because they reflect some of the blue from the sky. I know that the gas giants Neptune and Uranus look blue and/or green because of the concentration of methane in our atmosphere. Our atmosphere is 78% nitrogen, 21% oxygen, and 1% other gasses. It could be possible that the mixture of gasses in the atmosphere creates a light-bluish layer of gas when combined with the lighter, higher-up pressures. Even so, that is probably incorrect, because the clouds on Uranus and Neptune are... clouds. The color of our sky is something different.

The sky could be blue because the oceans are blue. Earlier I said that the oceans reflect the skies, but it could be the other way around. The oceans could be darkened by sediment in the water, or the lighter water could transmit the darkness from the deep. The blue of the oceans could reflect against the particles in the sky and create a canopy of blue. That is also probably incorrect. The different concentration of particles in the sky would create an uneven canopy of blue, with other colors poking through. Also, without like to broadcast the ocean's blue, the